Ferrar, H.T. 1925 The geology of the Whangarei-Bay of Islands subdivision, Kaipara division. Wellington: Government Printer. New Zealand Geological Survey bulletin 27 134 p.
Abstract: This bulletin describes the geology of a large area – 1,095 square miles – in North Auckland, which contains a great variety of rocks, giving rise to a number of soil-types, and will be found of much value when a soil-survey of North Auckland comes to be made. It also deals fully with the coal, limestone, clay, and other mineral deposits. The coal resources have been found to be smaller than expected, but the limestone deposits are very large, and the clays (which require further investigation) seem to be of great importance. (auth)